Sailboat with pivoted center fin



May 15, 1951 E. o. HURST SAILBOAT WITH PIVOTED CENTER FIN Filed Dec.

INVENTOR EARL OLIVER HURST Patented May 15, 1951 UNITED STATES PATENT OFFICE SAILBOAT WITH PIVO'TE'D CENTER'FIN Earl Oliver Hurst, Douglaston, N. Y. Application December 12, 1947; SerialiNo'. 791,256

3 Claims. 1

This invention relates to boats and especially to sailboats with pivoted center fin, the general object of the invention being to provide animproved construction of leeway control device for such boats.

According to the usual practice in constructing sailboats a centerboard is employed to control leeway, and this is mounted in a narrow casing or box which projects upwardly from the interior of the bottom of the boat. This box is built over a slot in the hull structure. The centerboard, usually pivoted at its forward end, is adjusted by vertical movement either to its lower, or operating position, or to its upper position, in which it projects through the slotinto' the box, also known as the well or trunk.

The centerboard is objectionable for many reasons. The slot extends lengthwise of. the boat and requires the cutting of several of the frame cross members, thus weakening the hull structure; It is extremely diflicult to constructan adequate joint between the bottom. of the centerboard box and the slot. The stress placed on this centerboard box when the boatis under hard pressureof canvas is considerable. Great leverage is obtained by thebla'deof the b'oard against this inner wall of the box and intime itb'ec'omes' racked and soon leaks at the ke'elson where-the well is afiixed to the boat-bottom It. is impossible to reach the surfaces of this joint. for painting purposes so that the joint usually deteriorates by decay, requiring repairs at more or less regular intervals. Another: obfjection to the centerboard: is: that it clutter-s the inside of the boat.

The present invention aims: to eliminate the centerboard with. its many faults; and provide aleeway control devicewhichis moreeffectiveand which, because of its simplicity; can be embodied in a boat at lower cost.

The invention will be understood from a-consideration of the accompanying drawings illil's trating one embodiment of the invention by way of example.

In these drawings:

Fig. 1 is a view in perspective, looking from showing the leeway controldevice inn different position Fig. 4 is a fragmentary perspective View to illustrate certain details of the device;

Fig. 5 is an enlarged section taken on line i i of Fig. 2; p

Fig. 6 is an enlarged fragmentary view of a part shown in Fig. 2;

Fig. 7 is an enlarged bottom view of this part, and

Fig. 8 is a section taken on line 88 of Fig. 6.

Referring" now to the accompanying drawingsthe sailboat I is constructed with the usual keel 2 and substantially fiat bottom hull sections 3 and 4 on opposite sides of the keel. These two hull sections are made flat, and the midsection" of keel 2 is straight, throughout the central portion of the boat, that is to say, throughout the per-- tion which, in a centerboard boat, would correspond to the position of the centerboa'rd, for a reason which will appear later on. The V-sha'ped bottom type of boat built of suitable laminated wood such as marine plywood is shown. The boat may also be of metal or may follow any of the many planked methods for fiat or V-type hull construction.

The leeway control device of the invention cornprises a structure having two fin elements "or surfaces, namely a fin element 5 and a relatively narrow fin element 6, that is two fin elements rigidly secured to one another in fixed angular relationship, one fin being substantiall greater in width than the other, and preferably several times greater. It will be understood that the width of fin element 5 will be chosen to'suit the size of the boat on which it is to be used taking into account the amount of sail, type of rigging etc. Thus for example these two fin elements may each consist of a fiat and substantially rigid plate, of steel, bronze or any appropriate material. Approximately one-quarterinch 4") steel plate is suitable (preferably galvanized or otherwise treated to resist corrosion).

The fin elements may be cut therefrom in any suitable shape or configuration but the width of element 5 should be not more than half the beam of the boat. The inner edges of the fin elements are rigidly secured on an appropriate mounting. They may be made straight and secured to a supporting rod 1 (Fig. 4) by welding, and in order to impart rigidity to the structure a fillet 8 of weld material may be laid along the surface of rod 1 between the two plates, or other suitable bracing means may be used.

The length of the leeway control device, that is to'say the length of the two fin elements '5 and 6, is such as to correspond'with the length of the usual centerboard section, although they can be made either shorter or longer depending upon the amount of the surface desired. The device is pivoted at its front and rear ends to the keel structure 2 so that it can be swung cross wise f the boat about these pivots. As illustrated in the drawings these pivots may be formed by extensions 9 at each end of supporting rod 1, one of which is shown in detail in Fig. 4 wherein the hinged keel device has been inverted for the sake of clearness of illustration. The front and rear pivotal extensions 9 are received in bearing blocks I!) (Fig. 4) which may be secured to the keel structure by means of bolts applied through the apertures H.

The angular relationship between the two fin elements and 6 is such that when element 5 is in the vertical position as shown in Figs. 1 and 2, thatis in alignment with a vertical plane through the keel, the other fin element 6 lies against one of the flat bottom hull sections, for example sec tion 4. Accordingly the angle between the two fin elements is equal to one-half the outside angle between the bottom hull sections. For a fiat bottomed boat the outside angle between the bottom hull sections on opposite sides of the keel is 180 and, therefore, the angle between the two fin elements of the leeway control device would be 90. For a V-bottom boat, the outside angle between the corresponding two bottom hull sections is greater than 180 and therefore the angle between the two fin elements is greater than 90, as is the case in the example shown in the drawmgs.

Cam action catches or securing devices, indicated generally by numeral l2 and manually operable from inside the hull, secure or, release the keel fin structure as desired. These catches clamp the edge of the narrow fin element 6 firmly against the bottom of hull section 4. Two or more of these catches may be provided depending on the size of the boat. When the narrower fin element 6 is swung into alignment with the planeof the keel the relatively wide fin element 5 is positionedagainst the fiat bottom hull section-3. One or more of the clamping devices 12 may be arranged to operate on the edge of fin element 5 to hold it firmly against the surface of flat bottom hull section 3. The hull structure is properly reinforced in the keel area to provide for the stresses involved. These devices will be described in detail later.

With this leeway control device the boat can be operated in a seaway with either the smaller or the larger fin surface. Also when entering shallow water the device can be adjusted for operation with the narrow fin element. The adjustment of the keel fin device from one position to the other may be controlled in various ways, for example, by means of a line 13, one end of which is fastened to the bottom of the wide in element 5 at the rear, and when operating the boat with this fin element in operative position, line i3 is carried'to the stern of the boat near rudder M and made fastto a oleat placed at any convenient point on the transom. When it is desired to swing the wide fin element 5 upwardly so as to bring fin element i5 into operative position, line [3 is loosed from the cleat and carried around the side of theboat as shown in the draw- 1118's, and by hauling upward on thisline over a roller sheave the fin element 5 is swung upwardly and then looked in position by turning securing device i2. Line i3 is then made fast to cleat I? as shown in Fig. 3. Line l3 may conveniently be 4 made of one-eighth inch flexible steel cable.

The cam action securing devices l2 are all alike and their construction is illustrated in detail in Figs. 5-8 inclusive. Referring to Fig. 5, each device is provided with an operating hand hold it which is accessible from the inside of the hull, a section of the floor boards ll being made removable, when necessary, for this purpose. Hand hold 56 is arranged at the upper end of an operating rod or shaft E8, the upper portion of which is journaled in abracket 19 which is secured in any suitable manner, as by means of the bolts 2E, to the hull. Referring to Figs. 2 and 5,

the hull section 4 is reinforced as indicated at 2 i, for example, by superposed layers of laminated wood bonded for marine use, in order adequately to support the two securing devices l2. Hull section 3 is similarly reinforced to accommodate the single securing device [2 on that side of the boat.

Operating shaft it extends downwardly through a stufing box and terminates at its lower end in aclamping head 22. The stufiing box has a stationary barrel 23 which is appropriately mounted in the reinforcement 2| and extends through the bottom of the hull section. The barrel is provided with suitable packing around shaft i8, and an adjustable sleeve 24 is pro-- vided to hold the packing in place in such a way as to prevent leakage around the shaft. H

Clamping head 22 is; shown in bottom view in Fig. 7 and when in the full line position engages the outer surface of one of the fin elements (fin element 5 in this instance); and when turned to the dot and dash position releases the finelee ment. Clamping head. 22 is formed with a sloping cam surface 25 as shown particularly in Figs. 6 and 8 and of ample surface area so that whe hand hold I5 is turned to rotate the clamping head from the dot. and dash position of Fig. :7 to the full line position, the outer surface of the fin element is engaged by this cam surface and the fin element is thereby forced firmly against the bottom of the hull.

By means of the leeway control device of the present invention, considerable additional space is provided within the boat which would otherwise be occupied by a centerboard trunk, and in small boats this additional space is particularly valuable. The device is simple and can be manufactured at low cost. By clamping one of the two fin elements against the bottom of the boat the other fin element is held securely in position to withstand the side thrusts to which it is subjected.

It will be understood that although the invention has been illustrated and described in considerable detail in connection with a single em-' bodiment, various changes can be made without departing from the spirit of the invention, the scope of which is set forth in the appended claims.

I claim:

1. In a boat having a straight keel section and two substantially flat bottom hull sections on opposite sides of said keel section, a leeway control structure comprising two fin elements one wider than the other and disposed in fixed angular relation to each other, saidrstructure being pivoted lengthwise of said'keel section and pivotally movable to position either of said fin elements in alignment with a vertical plane through the keel, the other of said fin elements being simultaneously positioned against one of said hull; sections, and releasable means for securing'zsaid;

other fin element against its corresponding hull section, comprising a shaft extending through the hull bottom, a stufiing box therefor, and a cam shaped head on the lower end of said shaft engageable with the margin of said fin element by rotation of said shaft.

2. In a boat having a straight keel section and two substantially fiat bottom hull sections on opposite sides of said keel section, a leeway control structure comprising two fin elements one wider than the other and disposed in fixed angular relation to each other, said structure being pivoted lengthwise of said keel section and pivotally movable to position either of said fin elements in alignment with a vertical plane through the keel, the other of said fin elements being simultaneously positioned against one of said hull sections, and releasable means for securing said other fin element against its corresponding hull section, comprising a shaft extending through the hull bottom, a stufiing box therefor, and cam means operable by said shaft and engageable with said fin element by rotation of said shaft.

3. In a boat having a hull with a straight keel section, a leeway control structure comprising two fin elements disposed in fixed angular relation to each other, said structure being pivoted lengthwise of said keel section and pivotally movable to place either of said fin elements in alignment with a vertical plane through the keel to control the leeway of the boat, and means for maintaining said structure in leeway control position comprising clamping mechanism on the boat hull for clampingly engaging the fin element of said structure which is not in leeway control position, one of said fin elements being of substantially dififerent width than the other so as to render the boat maneuverable in shallow or deep water as desired.

EARL OLIVER HURST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 595,161 Gibb Dec. 7, 1897 690,685 Anrep Jan. '7, 1902 709,417 Mayo Sept. 16, 1902 779,440 Pool Jan. 10, 1905 1,270,466 Van Buren June 25, 1918 

